In recent years, optical computing techniques have been developed for applications in the Oil and Gas Industry in the form of optical sensors on downhole or surface equipment to evaluate a variety of fluid properties. An optical computing device may be a device configured to receive an input of electromagnetic radiation from a substance or sample of the substance and produce an output of electromagnetic radiation from a processing element, also referred to as an optical element. The optical element may be, for example, an interference based thin film, or an Integrated Computational Element (“ICE”) (also known as a Multivariate Optical Element (“MOE”)).
Fundamentally, optical computing devices such as an ICE may utilize optical elements to perform calculations, as opposed to the hardwired circuits of conventional electronic processors. When light from a light source interacts with a substance, unique physical and chemical information about the substance may be encoded in the electromagnetic radiation that is reflected from, transmitted through, or radiated from the sample. Thus, the optical computing device, through use of the optical element and one or more detectors, may be capable of extracting the information of one or multiple characteristics/properties or analytes within the substance and converting that information into a detectable output signal reflecting the overall properties of a sample.
Optical computing devices such as ICEs may use spectrally resolved optical elements to analyze the electromagnetic radiation from a sample. These passive elements may require re-calibration procedures to correct for fabrication errors. Moreover, downhole hydrocarbon wells may have harsh and changing environmental conditions, such as temperature, pressure, and humidity adversely affect the performance and require that the passive elements be re-calibrated. These passive elements may include as many as 50 or more thin dielectric layers prone to contraction or expansion, according to different environmental conditions. Moreover, some ICEs may use multiple passive devices mounted onto a rotating wheel, which may increase device overhead in a limited space environment, such as in a downhole oil exploration and extraction application. Furthermore, rotating passive elements may be difficult to align with flowing fluid, which may require additional wheel synchronization adding complexity to data analysis, compromising results accuracy with undesirable latency in the slow rotation of typical filter wheels, and rotation jitter.
What is needed is an optical computing device that may be manufactured to be tunable to weight wavelengths of light transmitted through, absorbed by, or reflected by a sample corresponding to analytes of interest that allows spectral measurements of samples using a broad spectral band with a reduced number of physical components.